I have been mostly programming in Perl for the last three
years. Thanks to CPAN and
the acquired experience I can get quite a bit done in a
short amount of time. Now I am thinking about working in
Python and C++ again and the lack of a CPAN equivalent is
distressing.

So, I have started to think about a tool for those that
want to create services like CPAN. The basic features are

HTTP accessible archive of modules for both human
and
machine.

Modules have type, version, and dependencies.
Perhaps a
general set of named attributes.

Contributions can be upgraded directly by
contributor
and maintainer.

Contributions can be downgraded directly by
contributor
and maintainer.

Sites can be mirrored easily.

Module installation registry on local host.

Simple command line tool for incorporating new
modules
into an installation.

Simple command line tool for incorporating upgraded
and
downgraded modules into an installation.

As a general tool perhaps the most you could is to
coordinate the archive's content with a local and limited
copy of it, and then coordinate the incorporation of the
local modules into some default base installation. (SWIG has done a great job
over the years at unifying the creation of C and C++
extensions for scripting languages. I am sure there is much
experience and advice here we need to keep in mind.)

Anyway, it would be nice to have something to offer the
Python, C++, Ruby, JavaScript, etc communities.